Google wants a third damages report by an Oracle expert in the companies' lawsuit over the Android mobile OS to be thrown out, arguing that it is "riddled with fatal errors," according to a filing made Friday in U.S. District Court for the Northern District of California.

The case dates to August 2010, when Oracle sued Google claiming that Android was in violation of patents and copyrights Oracle holds on Java. Google has denied any wrongdoing and claimed that Android employs a "clean room" version of Java that doesn't violate Oracle's rights.

The court had previously rejected two damages reports by Oracle's expert, Boston University professor Iain Cockburn, saying he had overreached. Judge William Alsup has said he won't set a trial date for the case until an acceptable damages report is submitted.

Cockburn initially estimated that Google could owe Oracle as much as US$6.1 billion. But Alsup has said that Oracle should use $100 million as a starting point for its claims, with adjustments up and down as necessary. He has also appointed an independent expert who will weigh in on damages claims.

The third Cockburn report, which wasn't available Friday through an online records search, proposes two alternative approaches to calculating damages, according to Google's filing.

A second, described as a "group and value" method, puts total copyright and patent damages at between $52.4 million and $169 million, assuming the court requires a number of deductions Cockburn included in his calculations, Google said.

Both are "legally improper" proposals for damages calculations, according to Google.

In the first instance, Cockburn "purports to evaluate the 'independent significance of the patents-in-suit and copyrights to Google, but this 'analysis' is smoke and mirrors," Google said.

He "throws into the hopper every piece of evidence he can identify showing that Google considered certain obvious features -- speed, memory and number of applications -- important to a smartphone platform and that the inventions at issue improve those features," it added.

In his "group and value" methodology, Cockburn asked five Oracle engineers "to identify all the mobile Java-related patents in Sun's 2006 portfolio, separate those patents into categories, rank the categories in importance and then rate each patent's value on a three-point scale," Google said.

But several of the engineers admitted during depositions that "they spent next to no time compiling their rankings and were influenced by their prior work on this case," it added.

In addition, Oracle engineer Mark Reinhold, who is chief architect of the Java platform group at the vendor, "admitted there was no way to translate the engineers' judgment of comparative value into the hard numbers required for a damages analysis," the filing states.

Oracle spokeswoman Deborah Hellinger declined comment Friday on Google's motion. She could not immediately provide a copy of Cockburn's report.